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PS24

Egg Quality 1

Jacqueline P. Jacob, Richard D. Miles and F. Ben Mather2

While the avian is a vehicle for reproduction, even if the egg is infertile. If the egg is infertile, the it also serves as a source of for human germinal disk contains the genetic material from the consumption. The size and shape of avian hen only. If the egg is fertile, it contains genetic differs among the various species of , but all material from both parents and is where embryonic eggs have three main parts -- , albumen, and shell development begins. The yolk material serves as a (see Figure 1). These three parts of the egg are food source for . separated from each other by membranes. The shell is separated from the albumen () by the The egg white (albumen) is produced by the shell membranes, and the yolk is separated from the . There are four types of egg white (Figure albumen by the yolk membrane (). 1). The outer thin white is a narrow fluid layer next to the shell membrane. The outer thick white is a gel that forms the center of the albumen. The inner thin white is a fluid layer located next to the yolk. The inner thick white (chalaziferous layer) is a dense, matted, fibrous capsule of albumen around the vitelline membrane of the yolk. The matted fibrous capsule terminates on each end in the chalazae, which are twisted in opposite directions and serve to keep the yolk centered. The chalazae are twisted so that the germinal disk always orients itself upwards. During storage, however, the thick albumen becomes thinner allowing greater movement of the yolk. Figure 1. Parts of the egg. When the egg is laid it is at the same temperature The yolk is formed in the . There is a small as the hen's body (about 105°F). As the egg cools white spot about 2 mm in diameter on the surface of to ambient temperature, the egg contents contract and the yolk. This is the germinal disk and it is present the two shell membranes separate, generally at the

1. This document is PS24, one of a series of the Animal Sciences Department, Florida Cooperative Extension Service, Institute of Food and Agricultural Sciences, University of Florida. Original publication date April 1998. Revised May 2000. Reviewed March 2011. Visit the EDIS website at http://edis.ifas.ufl.edu. 2. Jacqueline P. Jacob, poultry extension coordinator, Richard D. Miles, professor, and F. Ben Mather, poultry extension specialist, of the Animal Science Department, Cooperative Extension Service, Institute of Food and Agricultural Sciences, University of Florida, Gainesville, 32611.

The Institute of Food and Agricultural Sciences (IFAS) is an Equal Opportunity Institution authorized to provide research, educational information and other services only to individuals and institutions that function with non-discrimination with respect to race, creed, color, religion, age, disability, sex, sexual orientation, marital status, national origin, political opinions or affiliations. U.S. Department of Agriculture, Cooperative Extension Service, University of Florida, IFAS, Florida A. & M. University Cooperative Extension Program, and Boards of County Commissioners Cooperating. Millie Ferrer-Chancy, Interim Dean Archival copy: for current recommendations see http://edis.ifas.ufl.edu or your local extension office.

Egg Quality 2 large end of the egg, forming the air . The outer color has nothing to do with egg quality, flavor, membrane sticks to the shell while the inner nutritive value, or cooking characteristics. membrane sticks to the albumen. During storage, the egg loses water by evaporation, causing the air cell to The appearance of the egg, as influenced by enlarge. severity of defects, is important for consumer appeal. Egg shells are evaluated on the basis of cleanliness, The shell is produced by the shell gland () shape, texture, and soundness (see Table 1). For of the oviduct, and has an outer coating, the bloom or approximate egg surface areas see Figure 2. cuticle. The cuticle somewhat seals the pores and is useful in reducing moisture losses and in preventing bacterial penetration of the egg shell. Much of the cuticle is removed from table eggs when they are mechanically washed. To replace the cuticle, table eggs are often sprayed with a light oil mist.

Egg Grades

Grading is a form of quality control used to divide a variable commodity or product into a number of classes. The United States Department of Agriculture (USDA) standards for quality of Figure 2. Approximate areas of the shell surface for individual shell eggs were developed on the basis of assessing stains. both interior and exterior quality factors. Commercially, eggs are graded simultaneously for Cleanliness exterior and interior quality. When determining the Most eggs are clean when they are laid, but they grade of an egg, the factor with the lowest grade will can become contaminated with manure or other determine the overall grade of the egg. In the United foreign material. In the United States, an egg with States, egg grades include AA quality, A quality, B manure or adhering material on the shell cannot be quality, and dirty. Only AA and A quality eggs are marketed. It is classified as dirty and cannot be used sold for supermarkets. for human consumption. Eggs with stained shells are Egg Shell Quality unattractive in appearance and cause eggs to be downgraded to B quality or dirty depending on the Shell color comes from pigments in the outer severity of the stain. layer of the shell. Shell color is primarily a breed characteristic, although there is often variation among Shape individual hens in a particular flock even when all are The "normal" egg is elliptical in shape. of the same breed and variety. Egg shells of Eggs that are unusual in shape, such as those that are commercial breeds of are white or brown. long and narrow, round, or flat-sided cannot be Breeds with white earlobes ordinarily lay white eggs placed in Grades AA or A. Round eggs and unusually while breeds with red earlobes ordinarily lay brown long eggs have poor appearance and do not fit well in eggs. White eggs are most in demand among cartons so are much more likely to be broken during American buyers. In some parts of the country, shipment than are eggs of normal shape. however, particularly in New England, brown shells are preferred. The Rhode Island Red, New Texture Hampshire and Plymouth Rock are breeds that lay brown eggs. Since brown-egg layers are slightly An egg shell that is smooth is preferred since larger birds and require more food, brown eggs are rough-shelled eggs fracture more easily and have poor usually more expensive than white. While darker appearance. Eggs with extremely rough, or uneven colored brown eggs tend to have thicker shells, shell shells are downgraded to B quality. Archival copy: for current recommendations see http://edis.ifas.ufl.edu or your local extension office.

Egg Quality 3

Some eggs have a rough pimply appearance. The Factors Affecting Shell Quality pimples ( deposits) are distortions to the shell. Infection is not responsible because pimpling Poor shell quality can result in downgrading. also occurs in disease-free flocks. The defect may be Table 2 lists some of the factors which may affect partly hereditary. shell quality. Producers should be aware of these factors so they can take preventive actions to Mottled shells have pale translucent spots minimize the occurrence of costly downgrades. (sometimes called "windows") of various sizes. Such Management plays an important role in controlling all eggs appear normal when laid. The mottling develops of these factors to produce eggs of high quality. To later and may be noticeable half an hour after laying, assure the production of high quality eggs, one although it is more easily detected a day later. This should select a strain of birds known to produce eggs abnormality is inherited, although a similar effect can of good quality because egg quality is a heritable be induced artificially, such as when a wet, newly laid characteristic. Avoid prolonged periods of egg slides across the wire cage floor instead of temperature above 86°F in the laying house, if rolling, or when a hen's toenail scratches the surface possible. Use high quality feeds and adjust feed of a recently laid egg. formulations according to feed intake and the age of the hens. Practice the necessary steps to prevent Soundness disease and other physiological disturbances in the flock. The time pullets start to lay can be regulated "Body checks" are eggs with shells that have by controlling feed and light in a planned program. been cracked during shell calcification in the hen and Because egg quality decreases with the age of the have had a layer of calcium deposited over the hen, the number of years to keep a hen should be crack(s) before the egg is laid. Some body checks are considered in relationship to all aspects of the covered by a relatively thick layer of calcium before production plan. being laid so are not easily detected unless eggs are candled. Other body checks are only covered by a thin If one disease had to be singled out as being calcium layer before being laid so they are easily responsible for the majority of the economically detected. significant production losses in egg layers, it would be infectious bronchitis. Not only is egg shell quality The incidence of body checks will increase if affected, but internal egg quality also declines. hens are excited in the afternoon or early evening just Watery whites are very common and can persist for as the egg shell begins to form in the oviduct. It is important, therefore, to keep hens as calm as possible, long periods after egg production returns. Also, an infectious bronchitis outbreak can result in a especially during the late afternoon and at night. pale-colored shell in brown eggs. However, other Body checks sometimes appear as ridges or factors, such as stress, are also responsible for bulges on the shell. Depending upon the extent and causing a pale-colored shell. severity of the ridge or bulge, or the ease of detecting Another disease which may affect shell quality is the checked area, body checks may be classified as B Egg Drop Syndrome 76 (EDS 76). EDS 76 was first quality. These shells are usually weaker than normal identified in Britain in 1976. A vaccine was quickly shells, are more likely to break in shipment, and they developed and the disease seemed to disappear. lack consumer appeal. However, it has recently reappeared in the Sometimes eggs have thin spots in the shell. The Netherlands. The disease is mainly characterized by a thin spots may appear gray and the shell is more drop in egg production early in lay, or by a sudden fall likely to break in these areas. in production at a later stage in the laying period. In the beginning the symptoms include shell-less eggs and thin-shelled eggs, deformed eggs, and, in the case of brown eggs, a loss of shell color. In addition, the whites of these eggs are very watery, and there is considerable variation in egg weight. Archival copy: for current recommendations see http://edis.ifas.ufl.edu or your local extension office.

Egg Quality 4

Interior Egg Quality Ambient temperature has also been shown to have an effect on the incidence of blood spots. Fewer Interior egg quality is based on air cell size, blood spots have been observed with Leghorn hens at albumen quality, yolk quality, and the presence of 32°C (89.6°F) than with Leghorn hens at 21°C blood or meat spots (see Table 3). (69.8°F).

Albumen Quality Factors affecting albumen quality are listed in Table 4. Excluding disease, the single most important The albumen has a major influence on overall factor affecting albumen quality of fresh eggs is the interior egg quality. Thinning of the albumen is a age of the hen. As the hen ages, albumen quality sign of quality loss. When a fresh egg is carefully decreases. An induced pause in egg production broken out onto a smooth flat surface, the round yolk (induced molt) has been shown to improve the is in a central position surrounded by thick albumen. albumen quality of subsequent eggs. Albumen When a stale egg is broken out, the yolk is flattened quality of the eggs is not greatly influenced by hen and often displaced to one side and the surrounding nutrition. Environment and housing, even heat stress, thick albumen has become thinner, resulting in a large appear to have almost no direct effect on albumen area of albumen collapsed and flattened to produce a quality of freshly laid eggs. wide arc of liquid. Watery egg whites have been shown to be caused Properly refrigerated eggs stored in their carton by high levels of vanadium in the feed. High levels in a home refrigerator will change from AA-grade to of vanadium can come from certain sources of A-grade in about 1 week and from A-grade to inorganic . Usually these sources are not B-grade in about 5 weeks. However, a properly mined, but certain high-vanadium deposits have handled and refrigerated intact egg will retain its occassionaly shown up in the feed industry. nutritional value and wholesomeness for a considerably longer time. Remember that eggs are perishable and will deteriorate in quality if not properly handled. Oiling The albumen occasionally contains blood and/or of eggs within 24 hours of lay is very effective in meat spots. Both chemically and nutritionally, these slowing down reduction in albumen quality, but does eggs are fit to eat. The spot can be removed, if you not replace the need for cool storage. wish, and the egg used. USDA regulations, however, classify eggs with blood or meat spots as inedible On very rare occasions, a hard-cooked egg white (see Table 3). may darken to a caramel shade due to a high amount of in the cooking water or to a chemical reaction Less than 1% of all eggs produced have blood involving components of the egg white. Using fresh spots. Blood spots result from hemorrhage of a small eggs and cooling them quickly after cooking helps to blood vessel in the ovary or oviduct. If the blood spot prevent this darkening. is on the yolk, the hemorrhage was probably in the ovary at the time of or in the infundibulum Yolk Quality part of the oviduct before albumen was laid down. If the blood spot is in the albumen, the hemorrhage Yolk quality is related to its appearance, texture, probably occurred in the wall of the magnum part of firmness, and smell. Table 5 lists some of the factors the oviduct. Meat spots are degenerated blood spots, affecting yolk quality. loose pieces of ovary or oviduct tissue, or cuticle The yolk of a freshly laid egg is round and firm. remnants swept up to the magnum and included in the As the yolk ages, it absorbs water from the albumen albumen. and increases in size. This weakens the vitelline Leghorn strains vary in the number of eggs they membrane and gives the yolk a somewhat flattened lay with blood spots. Eggs from brown-egg layers shape on top and a general "out-of-round" shape. will usually show a higher incidence of blood and Ruptured occasionally occur. meat spots than those from white-egg strains. Archival copy: for current recommendations see http://edis.ifas.ufl.edu or your local extension office.

Egg Quality 5

Severe chilling or freezing of intact eggs can Other consumers prefer a darker orange yolk. In most result in rubbery yolks. A similar condition can cases the diet is altered to produce egg yolks of the result if hens consume crude cottonseed oil in the diet correct color for a particular market. or if they consume seeds of velvetweed or other related plants. The yolks of eggs laid by hens Yolk pigments are relatively stable and are not consuming velvetweed seeds become rubbery, lost or changed in cooking. Sometimes, however, viscous and pasty in appearance after a short period of there is a greenish ring around hard-cooked egg cold storage. The eggs appear normal before yolks. It is the result of sulfur and iron compounds in refrigeration. Cottonseed, velvetweed, and other the egg reacting at the surface of the yolk. It may related plants contain cyclopropenoid compounds, occur when eggs are overcooked or when there is a which tend to increase the percent of saturated in high amount of iron in the cooking water. Although eggs, tissues and milk. the color may be a bit unappealing, the eggs are still wholesome and nutritious and their flavor is Velvetweed, which is also known as velvetleaf, unaffected. Greenish yolks can best be avoided by Indian mallow, butterprint, button weed and using the proper cooking time and temperature, and American Jute, is an annual that grows well in corn by rapidly cooling the cooked eggs. fields. Velvetweed generally reaches heights of 3-6 feet. Its leaves, which can reach up to 5 inches wide, Sometimes a large batch of may are heart-shaped and covered with soft velvety hairs. turn green. Although not pretty, the color change is Producers who raise their own grain need to make harmless. It is due to a chemical change brought on every effort possible to destroy velvetweed in the by heat and occurs when eggs are cooked at too high a field. Those who purchase corn need to be aware of temperature, held for too long after cooking, or both. the potential presence of velvetweed seeds in corn Using stainless steel equipment and low cooking screenings. temperature, cooking in small batches, and serving as soon as possible after cooking will help to prevent Double-yolked eggs occur when two yolks move this greenish discoloration. If it is necessary to hold through the oviduct together, either from scrambled eggs for a short time before serving, it simultaneous ovulations or delay in a yolk's passage helps to avoid direct heat. Place a pan of hot water through the oviduct. Such eggs are usually larger due between the pan of eggs and the heat source. to the presence of the two yolks. Eggs with three or more yolks are extremely rare and never reach the Mottling marketplace. It is essential that the vitelline membrane remain Color intact and strong in order to prevent the contents of the albumen and yolk from mixing. If mixing occurs, Yolk color depends on the diet of the hen. If she the quality of the egg and consumer acceptance of gets plenty of -orange plant pigments known these eggs declines because of "mottling." as , they will be deposited in the yolk. Hens fed mashes containing yellow corn and The degree of yolk mottling is related to the meal lay eggs with yellow yolks, while those eating amount of degeneration of the vitelline membrane. white corn, grain sorghum (milo), wheat or barley The greater the damage to the membrane, the more yield light-colored (platinum) yolks. Natural severe the mottling. yellow-orange substances such as marigold petals What Is Egg Mottling? may be added to light-colored feeds to enhance yolk color. When an egg is said to be "mottled", the yolk surface is covered with many pale spots or blotches. In any consumer survey of egg quality, yolk These areas are of different colors, or shades of color ranks high but preference varies among colors, and can vary in size. The spots can range countries. Some consumers prefer white-colored from being somewhat transparent, to a yolks while others prefer a light-colored yellow yolk. Archival copy: for current recommendations see http://edis.ifas.ufl.edu or your local extension office.

Egg Quality 6 brownish-orange to almost black in extreme cases. A high-tannin grain sorghum is removed from the slight degree of yolk mottling is normal and does not diet. contribute to the negative attitudes regarding consumer acceptance of eggs. A high incidence of A calcium deficient diet, when fed to laying yolk mottling decreases consumer acceptance, even hens, has resulted in a very high incidence of mottled though mottling has not been shown to affect the yolks within 12 days. It is not likely that this cause of egg's nutritional value or flavor. mottling will be of concern to the egg industry because ordinarily laying hens are provided about What Causes Mottling? 3.5% calcium in the diet.

The strength and integrity of the vitelline It is not often that the vitelline membrane can be membrane are very important in preventing egg yolk strengthened by the addition of something to the diet. mottling. Any factor that affects the membrane in a In one instance, however, it has been reported that negative manner will result in a higher incidence of the strength of the vitelline membrane was increased yolk mottling due to increased yolk membrane when a variety of wheat, 'Florida 301', was used as a permeability. feed ingredient in the diet of laying hens. No reason was given for the improvement in the strength of the Dietary Factors: membrane in the presence of wheat. The anticcocidial drug, Nicarbazin, has been Storage of Eggs and Age of Hen: shown to cause yolk mottling when fed at a concentration of 0.005% or greater in the diet. The Storage time and temperature will affect the degree of mottling is not the same in all eggs, and not degree of egg yolk mottling. Storing eggs at room all hens respond the same way to Nicarbazin. A temperature increases the incidence of mottling. direct relationship exists, however, between the During storage, the vitelline membrane becomes duration of feeding Nicarbazin, the level of weaker and eventually disintegrates. This is Nicarbazin in the diet, and the incidence of mottled especielly true at high storage temperatures. With eggs. Worming drugs, such as Piperazine and storage, water enters the yolk and causes mottling. dibutyltin dialaurate, have also been reported to cause With prolonged storage, albumen also enter yolk mottling. the yolk and contribute to the severity of mottling.

Cottonseed meal is an excellent source of The percentage of mottled eggs has been related in laying hen diets even though it is somewhat to the age of the laying hen. Younger hens have been deficient in the essential amino acid, . reported to produce a higher number of mottled eggs. However, if the pigment gossypol is present in After the hens have been in egg production for 11 cottonseed meal in high enough concentrations, the weeks or longer, the incidence of mottled eggs begins possibility of mottling will increase. When gossypol to decline. is present in the diet at a concentration of less than 0.005%, the addition of iron sulfate at a 4:1 ratio of Yolk breakage during egg frying is greater for iron salt to gossypol has been reported to prevent eggs from older hens as well as from eggs that have mottling. However, when the gossypol concentration been stored for more that 2 weeks, as compared to is above 0.005%, iron sulfate supplementation does freshly laid eggs. No research has been conducted not seem to prevent mottling. that indicates that the degree of yolk mottling is related to the breakage of the yolk during frying. Some grain sorghums, known as resistant sorghums, contain high levels of tannin. It has been Egg Candling reported that feeding laying hens diets that contain 1 External appearance is not an accurate indication or 2% tannins will increase the incidence of yolk of overall egg quality. It is customary, therefore, to mottling. The mottling will desappear when the make use of a practice known as candling in order to Archival copy: for current recommendations see http://edis.ifas.ufl.edu or your local extension office.

Egg Quality 7 determine interior egg quality. Candling has the result of a broken inner shell membrane. A free air advantage of being nondestructive and rapid. It has cell may also occur when the inner and outer shell also been automated. membranes do not properly attach to each other, allowing the air cell to move freely between them. Accurate candling is best done in a darkened room with a means of passing light through each egg. Eggs can be graded on the basis of air cell depth. Candling equipment may range from a simple The depth of the air cell is the distance from its top to homemade unit to a mechanical device which is part its bottom when the egg is held with the air cell up of a mechanized washing, grading, sizing, and (see Figure 3). In a fresh egg, the air cell is small, not packing unit. Regardless of the type of equipment more than 1/8-inch deep. As the egg ages, used, each egg must be examined. evaporation takes place and the water lost from the egg is replaced with air so that the air cell becomes Weak shells can be easily detected by candling. larger and the egg is downgraded. A leaker is a cracked egg in which the membrane is ruptured, allowing egg white to leak out. These eggs cannot be marketed.

When candling eggs by hand, the egg is held firmly between the thumb and index finger with the small end of the egg resting against the middle finger. Place the large end of the egg close to the candling aperture. The long axis of the egg should be at about a 45° angle to the candling aperture. The thumb and finger should be on opposite sides of the shell to prevent obstructing the view of the egg's contents. Quickly turn your hand and wrist in a arc of about Figure 3. Measuring air cell depth. 180° to set the contents of the egg in motion. Stop the hand and wrist motion at the end of the arc. Blood spots can be detected upon candling as a Observe the egg's contents as they rotate inside the dark, red-colored spot in the egg. Blood or meat shell membrane. spots that are in the albumen appear to move more rapidly on candling than the chalazae, which may be When the egg is fresh, the yolk cannot be seen mistaken for meat spots. Blood spots are most easily except as a faint shadow, because it remains close to detected if the eggs are stored for at least 24 hours the center of the egg. As the egg quality decreases, prior to candling. They will appear as rather distinct the yolk moves more freely and casts a darker spots that move rapidly past the light. Small blood shadow because it floats closer to the shell. But spots can easily be removed after the egg is opened much of this difference is due to changes in the so that the egg may be used, but if they aggregate albumen, rather than to changes in the yolk. The more than 1/8 of an inch in diameter, such eggs thinner the albumen, or the weaker the chalazae, the cannot be marketed for human consumption. closer the yolk will be to the shell when the egg is twirled, due to centrifugal force. The yolk shadow is Egg Sizes more distinctly projected onto the shell when it is close to the shell than when it is closer to the center, In the United States, eggs are sold by size. The thus it appears darker. A darker shadow can also weight for each size classification is based on weight occur when eggs contain enlarged yolks or when the per dozen rather than weight per egg (see Table 6). vitelline membrane is weak. The greatest consumer demand is for Large and Extra Large eggs. This is due, in part, to confusion between The air cell is usually at the large end of the egg egg size and egg quality and to a lack of and can be plainly seen when an egg is candled. An understanding of egg quality grades. Some people air cell that moves freely to any part of the egg is the believe bigger is better. As a result, on a cost per Archival copy: for current recommendations see http://edis.ifas.ufl.edu or your local extension office.

Egg Quality 8 pound of egg basis, Medium and Small eggs may be a better food buy. It is important, however, to take into account the fact that there is more inedible shell per unit weight with smaller eggs. Archival copy: for current recommendations see http://edis.ifas.ufl.edu or your local extension office.

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Table 1. Summary of standards for exterior quality of chicken eggs.

GRADE FACTOR AA or A B Dirty Stain - Must be clean - Slight stains - Prominent stains - May show small specks, stains or - Moderate stains: - Moderate stains: cage marks that do not detract from - localized (single) - localized (single) general appearance of the egg < 1/32 of shell >1/32 of - May show traces of processing oil - scattered (2 or shell more) - scattered < 1/16 of shell >1/16 of (See Figure 2 for shell approximate surface (see Figure 2 for areas) approximate surface areas)

Adhering dirt or foreign NONE NONE Adhering dirt or foreign material material Egg shape Approximately the usual elliptical Unusual or decidedly shape misshapen (very long or distorted) Shell texture May have rough areas and small - Extremely rough areas that calcium deposits that do not may be faulty in soundness or materially affect shape or strength strength - May have large calcium deposits Ridges May have slight ridges that do not May have pronounced ridges materially affect shape or strength Shell thickness Must be free from thin spots May show pronounced thin spots

Table 2. Causes of shell quality problems.

CONDITION OF SHELL POSSIBLE CAUSES

A. Odd shaped 1. Inherited 2. Disease: Newcastle disease, infectious bronchitis, laryngotracheitis, Egg Drop Syndrome 76 3. Age of hens: incidence is higher in older hens

B. Thin, porous or shell-less 1. Inheritance influences porosity and ability to produce strong shells 2. Lack of sufficient calcium, phosphorus, manganese or D 3 3. mistakenly substituted for D 2 3 4. Excess phosphorus consumption, especially by older hens 5. Ingestion of sulfanilamide (sulfa drugs) 6. Disease: Newcastle disease, infectious bronchitis, avian influenza, Egg Drop Syndrome 76 7. Hens exposed to temperature over 85-90¡F 8. Age of hens: incidence higher with older hens 9. Premature laying of the egg Archival copy: for current recommendations see http://edis.ifas.ufl.edu or your local extension office.

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Table 2. Causes of shell quality problems.

CONDITION OF SHELL POSSIBLE CAUSES

C. Rough or abnormal shell texture 1. Inherited 2. Newcastle disease or infectious bronchitis 3. Excessive use of antibiotics 4. Excess calcium consumption by the hens 5. Copper deficiency

D. Mottled shells 1. Primarily caused by high or low extremes in humidity 2. Inherited 3. Manganese deficiency 4. Artificially induced

E. White strain layers producing tinted 1. Primarily inherited. eggs

F. Yellow shells 1. Extended use of high levels of certain antibiotics G. Tremulous or loose air cells 1. Newcastle disease 2. Infectious bronchitis 3. Rough handling of eggs 4. Eggs stored large end down

H. Depigmented brown shell 1. Infectious bronchitis 2. High stress in the flock 3. Egg Drop Syndrome 76

Table 3. Summary of standards for interior quality of chicken eggs by candling.

INTERIOR QUALITY AA Quality A Quality B Quality Inedible FACTOR Air cell 1/8 inch or less in 3/16 inch or less in depth More than 3/16 inch Doesn't apply depth

White (albumen) - Clear- Firm - Clear- May be - Clear- May be weak Doesn't apply reasonably firm and watery Yolk Outline slightly Outline may be fairly Outline clearly visible Doesn't apply defined well-defined Spots (blood or meat) None None Blood or meat spots Blood or meat spots aggregating not more aggregating more than than 1/8 inch in 1/8 inch in diameter diameter

Table 4. Causes of albumen (egg white) quality problems.

CONDITION OF ALBUMEN POSSIBLE CAUSES Archival copy: for current recommendations see http://edis.ifas.ufl.edu or your local extension office.

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Table 4. Causes of albumen (egg white) quality problems.

CONDITION OF ALBUMEN POSSIBLE CAUSES A. Increased thin white 1. Inherited 2. Diseases: Newcastle disease, infectious bronchitis, laryngotracheitis or Egg Drop Syndrome 76 3. High egg storage temperature 4. Age of hens: incidence higher with older hens 5. High level of ammonia from droppings 6. Loss of CO from egg 2 7. High vanadium levels in the feed

B. Greenish albumen in fresh eggs 1. Riboflavin (vitamin B ) in feed: this is natural and is not undesirable 2 C. Cloudy white 1. High CO inside egg: may result from oiling egg too soon after lay 2 2. Refrigeration of fresh eggs at low temperatures (32 to 39¡F)

D. white 1. Cottonseed oil (contains the fatty acids malvalic and sterculic acid) E. Blood spots 1. Inherited 2. Increased blood spots occur with sudden environmental temperature changes 3. Age of hens: incidence higher with older hens 4. Deficiencies of (probably rare) or 5. Sulfaquinoxaline may increase incidence if vitamin K is marginal

F. Meat spots 1. Inherited 2. Bits of ovary, oviduct or cuticle 3. Blood spots dissolved from blood pigment

G. Spoilage by bacteria and molds 1. Green whites (under UV light) Pseudomonas bacteria 2. Black rots caused by Proteus bacteria 3. Molds can cause either green or black appearance when candled

Table 5. Causes of yolk quality problems.

CONDITION OF YOLK POSSIBLE CAUSES

A. Blood spots 1. Inherited 2. Increased blood spots occur with sudden environmental temperature changes 3. Age of hens: incidence higher with older hens 4. Deficiencies of vitamin K (probably rare) or vitamin A 5. Sulfaquinoxaline may increase incidence if vitamin K is marginal

B. Yolk color variation 1. Pigment level in diet 2. White yolks: a. Unknown disease condition b. Capillary worms c. White corn, grain sorghum, wheat or barley in ration, without pigment supplement 3. Olive or colored yolks: caused by 5 percent or more cottonseed meal containing gossypol or cyclopropene fatty acids in the diet Archival copy: for current recommendations see http://edis.ifas.ufl.edu or your local extension office.

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Table 5. Causes of yolk quality problems.

CONDITION OF YOLK POSSIBLE CAUSES

C. Mottled yolks 1. Nicarbazin (anticoccidial drug) 2. Gossypol (cottonseed meal) 3. Worming compounds: piperazine, citrate, phenothiazine, dibutylin dilaurate 4. Tannic acid 5. Calcium deficiency 6. Age of hens: incidence is lower in older hens 7. Inherited 8. Storage time, increases with time

D. Thick, pasty, rubbery or cheese-like 1. Crude cottonseed oil yolks 2. Severe chilling or freezing of intact egg 3. Seeds of velvetweed and other related species

E. Off-odors 1. Chemicals for treating parasites 2. Fruits, vegetables, and flowers: never store in egg cooler 3. Household detergents: use only special egg washing detergent/sanitizer materials 4. Moldy flats, cases or egg room

F. Flat yolks 1. Weak vitelline membrane: age of eggs, improper storage temperature, age of hens 2. Indirect effect of poor egg shell quality 3. Nicarbazin (anticoccidial drug)

Table 6. USDA classification of egg sizes.

Net weight (ounces)

Classification per dozen per egg

Jumbo 30 2.5

Extra large 27 2.2

Large 24 2.0

Medium 21 1.7

Small 18 1.5

Peewee 15 1.2